This project investigates myocardial perfusion-metabolic imaging with a new fatty acid, Iodine-123 phenylpentadecanoic acid (IPPA). The normal myocardium uses fatty acid as its preferred substrate. During myocardial injury, metabolism is altered so that: (a) clearance of fatty acids from ischemic myocardium is decreased compared to normal myocardium, and (b) fatty acid uptake is decreased in areas of infarcted myocardium. Preliminary evidence also suggests that fatty acid clearance and uptake are altered in myocardium injured by primary myocardial heart disease. IPPA, a new synthetic fatty acid developed at the University of Texas Health Science Center at Dallas (UTHSCD), has shown promise as a myocardial imaging agent in the animal model. The hypothesis of this project is that IPPA with single photon emission computed tomography (SPECT) can detect and measure mass of normal, ischemic, infarcted, and injured myocardium in patients with cardiac disease. Myocardial perfusion-metabolism will be assessed by uptake and clearance of IPPA using SPECT. IPPA with tomography will be evaluated in patients with: (a) acute myocardial infarction with and without reperfusion; (b) chronic coronary artery disease with exercise-induced ischemia; and (c) significant aortic regurgitation or mitral regurgitation. This study will determine in these patient subgroups: (a) the nature and extent of global or segmental perfusion-metabolic dysfunction; (b) the sensitivity and specificity of this technique in detection of clinically significant heart disease; (c) the usefulness of IPPA imaging in predicting future cardiac events: and (d) the interrelationships between metabolism, perfusion, and ventricular performance. Drs. Willerson, Corbett, and Parkey at UTHSCD have had extensive experience with all of the contemporary nuclear cardiology techniques. Recent work at UTHSCD has focused on the development of quantitative three-dimensional analysis of ventricular performance, including myocardial perfusion, metabolism, and function. Dr. Jansen, with the guidance of these three mentors, has begun research to develop quantitative tomographic techniques. The central focus of this project will be an investigation of myocardial scintigraphic perfusion-metabolism with tomographic fatty acid imaging. The development of generally available myocardial metabolic techniques will provide a powerful tool in noninvasive cardiac diagnosis, and in the evaluation of interventional therapeutic modalities.